Imaging systems today often include an array of pixel cells arranged in a predetermined number of columns and rows. Each of the pixel cells can be configured to sense an amount of light impinging on that pixel cell, and generate an appropriate image signal corresponding to that amount of sensed light.
Each column of the pixel array can include its own column line, where this column line couples all pixel cells of their respective column together. Each column line, in turn, can be coupled to column circuitry, such that each column of the pixel array is associated with its own instance of column circuitry. When a pixel cell has generated an image signal, at the appropriate timing the pixel cell can output this image signal onto the column line and to the column circuitry. The column circuitry may then perform any suitable processing of the image signal such as, for example, sampling the image signal, storing the image signal (e.g., on a capacitor), amplifying the image signal, performing correlated double sampling (“CDS”) on the image signal, passing the image signal to further image processing systems, and the like.
In some cases, however, an instance of column circuitry associated with a particular column can be defective or otherwise operate non-ideally. In other words, due to the defective column circuitry, image signals from that particular column may become corrupted and inaccurate, or it may even be impossible to obtain image signals from the pixel cells of that column. Accordingly, using the corrupted image signals can result in image degradation and loss of quality and accuracy. In some cases, to avoid such corrupted image signals, data from the affected columns can simply be discarded and not used. Interpolation or other estimation techniques may then be applied to attempt to estimate the correct values sensed by the pixel cells coupled to the defective column circuitry. However, once again, such estimation techniques can result in inaccuracies in the image data and in image degradation.